/*
 * Copyright (C) the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package net.derquinse.common.orm;

import java.io.Serializable;

/**
 * Abstract class for entities with a primary identifier.
 * @author Andres Rodriguez
 * @param <ID> Primary Key type.
 */
public abstract class AbstractEntity<ID extends Serializable> implements Entity<ID> {
	/** Contructor. */
	protected AbstractEntity() {
	}

	/**
	 * Checks if an object is an instance of an entity type and its id is equals to this entity id.
	 * @param type Entity type.
	 * @param obj Object to check.
	 * @return The object casts to type if the object is an instance of type and the object and this
	 *         entity have the same id (even if the id is null). Null otherwise.
	 */
	protected final <T extends Entity<ID>> T idEquals(Class<? extends T> type, Object obj) {
		return Entities.idEquals(this, type, obj);
	}

	/**
	 * Returns the hash code of the id of the entity. If the id is null a constant number is returned.
	 */
	protected final int idHashCode() {
		return Entities.idHashCode(this);
	}

}
